1. Field of the Invention
The present invention is directed to a method of inhibiting gene expression promoted by the AP1 protein complex, with compounds which specifically or selectively transactivate RAR.beta. retinoid receptors. The present invention is also directed to a method of administering pharmaceutical compositions for the treatment or prevention of certain diseases and conditions which comprise a compound or ligand capable of inhibiting gene expression promoted by the AP1 protein complex through RARs, and which compound specifically or selectively induces gene expression only through the RAR.beta. retinoid receptors. The present invention is further directed to a method of selecting compounds of beneficial retinoid-like activity by assaying candidate compounds for ability to antagonize the gene expression medicated through the AP1 protein complex to surpress the expression of gene promoted by the AP1 protein complex, and for the ability, or lack thereof of the compounds to transactivate gene expression through RAR.alpha., RAR.beta. and RAR.GAMMA. receptors.
2. Related Art
Compounds having retinoic acid like (retinoid-like) biological activity have been known for a long time, and are described in numerous United States and foreign patents and scientific publications. Generally speaking, it has been established and accepted in the art that retinoic-acid like compounds (retinoids) are useful in humans and domestic animals for the treatment or prevention of many diseases and conditions, as regulators of cell proliferation and differentiation, and particularly as agents for treating dermatoses, such as acne, Darier's disease, psoriasis, icthyosis, eczema and atopic dermatitis, and for treating and preventing malignant hyperproliferative diseases such as epithelial cancer, breast cancer, prostatic cancer, head and neck cancer and myeloid leukemias, for reversing and preventing atherosclerosis and restenosis resulting from neointimal hyperproliferation, for treating and preventing other non-malignant hyperproliferative diseases such as endometrial hyperplasia, benign prostatic hypertrophy, proliferative vitreal retinopathy and dysplasias, for treating autoimmune diseases and immunological disorders (e.g. lupus erythematosus) for treating chronic inflammatory diseases such as pulmonary fibrosis, for treating and preventing diseases associated with lipid metabolism and transport such as dyslipidemias, for promoting wound healing, for treating dry eye syndrome and for reversing and preventing the effects of sun damage to skin.
A classic measure of retinoic-acid like activity involves the effects of retinoic acid on ornithine decarboxylase. The original work on the correlation between retinoic acid and decrease in cell proliferation was done by Verma & Boutwell, Cancer Research, 1977, 37,2196-2201. That reference discloses that ornithine decarboxylase (ODC) activity increased precedent to polyamine biosynthesis. It has been established elsewhere that increases in polyamine synthesis can be correlated or associated with cellular proliferation. Thus, it was recognized early in the art that if ODC activity could be inhibited, cell hyperproliferation could be modulated. Although all causes for ODC activity increases are unknown, it is known that 12-O-tetradecanoylphorbol-13-acetate (TPA) induces ODC activity. Retinoic acid inhibits this induction of ODC activity by TPA. An assay essentially following the procedure set out in Cancer Res: 1662-1670,1975 has been extensively used in the art to demonstrate inhibition of TPA induction of ODC by tests compounds, which compound, if found inhibitory in the assay, is considered a "retinoid". Several other assays also exist in the art to determine if a compound has retinoid-like biological activity.
The use of retinoids in therapy of humans or domestic animals, is however, usually not without unpleasant or even serious side effects. Therefore, efforts have been made in the art to develop compounds which retain the beneficial activity of retinoids, but nevertheless lack the undesired side effects. U.S. Pat. No. 5,324,840 (assigned to the same assignee as the present application) for example discloses compounds which have retinoid-like activity but either lack, or have diminished skin-toxicity or teratogenic activity. An application for United States patent titled "Method of Treatment with Compounds Having Selective Agonist-like Activity on RXR Retinoid Receptors" Ser. No. 08/016,404 has been allowed and is expected to issue.
Significant efforts have also been made in the prior art to elucidate, on a biological, pharmacological or molecular level, the mechanisms by which retinoids act in living organisms, and specifically by which retinoids act to bring about beneficial therapeutic results and the undesired side effects. In connection with the foregoing it has been established in the prior art that one mode of action of retinoids is inducing gene expression through a class of receptors which are termed "RAR", another is through a class of receptors termed "RXR". Both the RAR and RXR receptor "families" have been shown to include several subtypes, which in the case of the RAR receptors are termed RAR.alpha., RAR.beta. and RAR.GAMMA.. Generally speaking, the following publications pertain to retinoid receptors and/or to compounds for selectively activating one or more of the receptor subtypes: D. J. Mangelsdorf et al. "Nuclear receptor that identifies a novel retinoic acid response pathway", Nature Vol 345 May 17, 1990 pp 224-229; and J. N. Rottman et al. A retinoic acid-responsive element in the apiloprotein AI gene distinguishes between two different retinoic acid response pathways, Molecular and Cellular Biology, July 1991, pp 3814-3820, M. Petkovich et al. "A human retinoic acid receptor which belongs to the family of nuclear receptor", Nature, Vol. 330, Dec. 3, 1987, pp 444-450; V. Giguere et al. "Identification of a receptor for the morphogen retinoic acid", Nature, Vol 330, Dec. 17, 1987, pp 624-629; N. Brand et al. "Identification of a second human retinoic acid receptor", Nature, Vol 332, Apr. 28, 1988, pp 850-853; A. Krast et al., "A third human retinoic acid receptor, hRAR", Proc. Natl. Acad. Sci. U.S.A., Vol 86, July 1989, pp 5310-5314; D. J. Mangelsdorf et al., "Characterization of three RXR genes that mediate the action of 9-cis-retinoic acid", Genes & Development, Vol. 6, 1992, pp. 329-344, D. J. Mangelsdorf et al. "Nuclear receptor that identifies a novel retinoic acid response pathway" Nature Vol. 345, May 17 1990, pp224-229, and International Publication WO 93 21146 (Ligand Pharmaceuticals) titled "Compounds Having Selectivity for Retinoid X Receptors".
As a still further development in the art pertaining to the mechanism of action of retinoids at the pharmacological and molecular level, it has been discovered that in the presence of a proper ligand (retinoid compound), the RARs regulate gene expression either by directly binding to the RA-responsive element (RARE) or by antagonizing the action of c-Jun/c-Fos (AP1) protein complex. More specifically, in the action of a retinoid (ligand) that acts through the RARs, one or more of the three different RAR subtypes (RAR.alpha., RAR.beta. and RAR.GAMMA.) bind to the retinoid ligand. The resulting RAR-ligand complex regulates gene expression either by activating the expression of genes containing RAREs in their promoter regions, or by inhibiting the expression of certain genes by antagonizing AP1 protein complex (c-Jun/c-Fos, hereinafter "AP1 protein" or "AP1 protein complex") mediated gene expression. (See the articles: Mangelsdorf et al. (1994). The Retinoids; Biology, Chemistry, and Medicine, pp. 219-349. Raven Press Ltd., New York; Chambon, P. (1994) Semin, Cell Biol. 5, 115-125, and Pfahl. M. (1993) Endocr. Rev. 14, 651-658). Antagonizing the AP1 protein and thereby suppressing or inhibiting expression of the AP1-promoted gene is considered a second mechanism of action of retinoids. The latter is generally considered to be beneficial from a therapeutic standpoint, because the genes stimulated by the AP1 protein are involved in hyperproliferative and inflammatory diseases such as psoriasis, rheumatoid arthritis and tumor metastases. Published International Patent Application Nos. WO 92/05447 and WO92/07072 relate to the subject of inhibiting the gene expression which is stimulated by the AP1 protein complex.
In contrast to the action of retinoid compounds (ligands) to prevent or inhibit expression of the gene promoted by AP1, the transactivation of genes containing the RAREs, on the other hand, can lead to some of the undesired side-effect of retinoids. Therefore, a need exists in the prior art to separate the two types of retinoid actions, whereby retinoid drugs of lesser toxicity and therefore of greater therapeutic benefit may be obtained.